Can I run the following CPU passively cooled ?

jones_r · Post by **jones_r** » Mon Aug 13, 2007 4:21 pm

I've noticed that when most people here say the words "passive CPU cooling", they actually mean one or two 120mm fans blowing air in the case.

This is not the case in my situation. I would like to operate my computer without a single fan, and would like to know what you think.

The system I'm building is:

- AMD 3600 X2 Birsbane CPU @ lowest voltage and CPU multiplier possible. Cooled by Scythe Ninja heatsink.
- Foxconn K8M890M2MA-RS2H motherboard (integrated VIA vga).
- 1 stick of giga ram.
- picoPSU power supply.
- PCI gigabit ethernet card.

I'm planning to build everything in an ordinary PC case, but operate it without both side panels.

Assuming the ambient temp in the computer room can get to 30 degrees celsius in the summer, do you think this entire computer could run completely fanless ?

jessekopelman · Post by **jessekopelman** » Mon Aug 13, 2007 6:53 pm

Ambient temperature of 30C is still nice and cool for PC components. The real question is how is the air flow in the room? I notice that when the window is open near my computer its temps are about 3 degrees lower. I'd say as long as there is always some airflow in the room when the computer is on, you'll be ok.

Lawrence Lee · Post by **Lawrence Lee** » Mon Aug 13, 2007 7:19 pm

What hard drive are you planning to use and how will it be mounted? I've found that any 7200RPM drive is louder than a properly silenced active cooling setup.

vortex222 · Post by **vortex222** » Mon Aug 13, 2007 9:40 pm

that should work fine, but it would be probably more beneficial to have some sort of side panels in place, with good bottom intake, and have the top of the case removed to create a wind tunnel effect.

But in all reality, a nexus or noctua at 5 volts is inaudible, and will quadruple the effectiveness of that heatsink and allow you to run it at nearly full clock for a much faster machine.

Very low flow fans pretty much are inaudible and are capable of cooling your low powered system very well. Also what hardrive are you planning on using?

jones_r · Post by **jones_r** » Tue Aug 14, 2007 12:16 am

I'm planning to use this hard drive:

embedded looooong URL

jaganath · Post by **jaganath** » Tue Aug 14, 2007 12:46 am

that MB doesn't allow BIOS undervolting, so you are gambling that software undervolting will be 100% stable.

Sylph-DS · Post by **Sylph-DS** » Tue Aug 14, 2007 4:14 am

Just out of curiosity, why did you decide to go with a dual core processor? You should be able to get a cooler (45W tdp as opposed to 65w) single core like the 3800+ 65nm edition ( http://products.amd.com/en-us/DesktopCP ... aspx?id=66 ).

Wouldn't a single core be more efficient? (that is a genuine question, I'm really not sure

)

jones_r · Post by **jones_r** » Tue Aug 14, 2007 9:10 am

that MB doesn't allow BIOS undervolting, so you are gambling that software undervolting will be 100% stable.

I didn't know that software undervolting could be less stable than hardware undervolting...

Just out of curiosity, why did you decide to go with a dual core processor? You should be able to get a cooler (45W tdp as opposed to 65w) single core like the 3800+ 65nm edition ( http://products.amd.com/en-us/DesktopCP ... aspx?id=66 ).

As far as I know, if I undervolt the X2 3600 Brisbane to 0.8V, the power consupmtion will not be higher than a single core clocked similarlly. The difference is mainly at max consumption, but I'm not going to get there anyway.

Regarding efficiency, I think two processors operating at 0.8V, is better than one processor operating at higher voltage, because higher voltage will cause more current leak.